Herpes viruses cause a number of significant disorders. Herpes simplex viruses (HSV) can be neurovirulent (e.g., infect and replicate in central nervous system tissue), although HSV infections of the brain are rare. HSV infections in neonates and immunosuppressed individuals can be severe. Herpes simplex virus-1 (HSV-1) is primarily responsible for orolabial herpetic lesions, although genital herpes may also be caused by HSV-1. Herpes simplex virus-2 (HSV-2) is the primary cause of genital herpes, and genital herpes caused by HSV-2 are generally more severe than genital herpes due to HSV-1. Additionally, HSV-2 represents a greater public health threat, as HSV-2 infection is associated with certain genital tract cancers and can be transmitted from mother to child during vaginal delivery.
A primary infection with the herpes virus varicella zoster virus (VZV) results in the human disease varicella, also known as chicken pox. Primary infection leads to latent infection of dorsal root ganglia cells, giving rise to a reservoir of virus which can be reactivated. Reactivation of latent VZV gives rise to a condition referred to as herpes zoster or shingles. Both primary and reactivated VZV infections give rise to cutaneous lesions, although varicella symptoms can include mucosal lesions as well.
Genital HSV-2 is among the most commonly sexually transmitted infectious diseases in women. Clinical infection occurs in 20–30% of adults (Parr et al. (1997) J. Reprod. Immunol. 36:77–92; Burke et. al. (1994) J. Infect. Dis. 170:1110–1119), while up to 85% of females can develop HSV-2 antibodies in their lifetime (Kinghorn (1996) Scand. J. Infect. Dis. Suppl. 100:20–25). The frequency of recurrences can be as often as monthly, at times lasting several days. Stanberry et al. (1986) J. Infect. Dis. 153:1055–1061. Complications may be significant, frequently resulting in sociopathologic morbidity, adenopathy, encephalitis neurologic syndromes. Neonatal infection may be high as 1:2000 births, usually caused by retrograde spread of HSV-2 or from fetal passage through an infected genital tract. Mortality (up to 85% in untreated infected newborns) results from disseminated intravascular coagulation, destructive encephalitis and other neurological maladies. Stanberry (1993) Rev. Med. Virol. 3:37–46.
The incidence of genital HSV-2 continues to escalate. An estimated 700,000 new cases occur each year in the U.S. alone. Reactivation is common, resulting in an estimated 25 million cases of recurrent genital herpes each year. Transmission commonly occurs through unprotected sexual contact, particularly during periods of asymptomatic viral shedding, and results in heightened morbidity and mortality when perinatal fetal transmission occurs. Current treatment of genital HSV-2 includes antiviral drugs that are merely palliative, controlling symptoms and exacerbations without providing a cure. Additionally, these chemotherapeutics are costly and may be associated with adverse reactions and potential drug interactions. Vaccines are a more desirable alternative to drug treatment or prophylaxis, and have been developed against HSV-2 to limit transmission or recurrence. Specific vaccines that have shown efficacy in animal models and clinical studies used attenuated virus, recombinant HSV-2 surface proteins or their corresponding cDNA. Their utility, however, is counterbalanced by the need of parenteral administration, often with poorly tolerated and unapproved adjuvants, and with less than desired clinical efficacy in humans and patient acceptability.
Clinical control of HSV-2 currently is limited to the use of topical, oral or intravenous antiviral drugs. These agents may be effective in controlling symptoms, and may diminish transmission and recurrence rates, but are not curative. These drugs also do not prevent transmission, particularly during asymptomatic viral shedding. Clear prevention of transmission or recurrence from latency would be a preferred method of clinical control. Immunologic prophylaxis against HSV-2 through vaccination has, therefore, emerged as a therapeutic alternative to chemotherapy. More specifically, highly targeted immunogenic components responsible for virus-host propagation, such as glycoprotein D, have provided the most appropriate strategy for immunization. Stokes et al. (1997) Virus Res. 50:159–174.
A host of studies using attenuated or inactive viruses or their components have demonstrated some utility as vaccines. Stanberry (1995) Trends Microbiol. 3:244–247. More recently, recombinant HSV-2 surface protein vaccines, particularly HSV-2 glycoprotein D (gD2), have shown greater efficacy in stimulating immune responses while limiting duration and severity of recurrences. Stanberry et al. (1988) J. Infect. Dis. 157:156–163; Straus (1994) Lancet 343:1460–1463; Straus (1997) J. Infect. Dis. 176:1129–1134; Langenberg (1995) Ann. Intern. Med. 122:889–898. The gD2 is an integral membrane protein, present in the viral envelope and is required for viral attachment and subsequent propagation in the host cell. The mature protein is composed of 368 residues, the C-terminal portion containing the transmembrane region. Multiple glycosylation sites (three N-linked and two to three O-linked) exist. While peptide fragments or bacterially-expressed expressed gD proteins possess antigenic properties, glycosylation appears necessary in eliciting maximal immunogenic responses, suggesting that eukaryotic cell expression vectors are more appropriate for generating this protein antigen. Stokes et al. (1997); Damhoff et al. (1994) J. Chromatogr. 676:43–49.
Others have demonstrated that nucleic acid vaccines, such as plasmid DNA encoding gD2, can also effectively immunize against HSV-2 by stimulation of both cellular and humoral immune responses. Bourne et al. (1996) J. Infect. Dis. 173:800–807; Bourne et al. (1996) Vaccine 14:1230–1234. However, all these vaccines were designed for parenteral administration, often containing unapproved or poorly tolerated adjuvants.
Meanwhile, nontraditional routes of antigen delivery, such as mucosal vaccination, have emerged as effective immunization alternatives. A body of evidence suggests that mucosal vaccination may provide more effective immunization against pathogens such as HSV-2, in essence, by inhibiting cellular attachment or neutralizing toxins at the point of exposure, e.g., within the genital mucosa, prior to pathogen and host interaction. Clements (1997) Nature Biotech. 15:622–623. These immune responses were amplified significantly with co-administration of adjuvants, such as cholera toxin β-subunit.
The concept of providing immune protection specifically through vaginal vaccination also has been proposed to be an effective alternative to parenteral vaccination. Parr et al. (1997); Clements (1997) Nature Biotech. 71:1497–1504; Uehling et al. (1991) J. Urol. 146:223; Uehling et al. (1994) J. Urol. 152:2308–2311; Uehling et al. (1994) J. Urol. 151:213. In animal models, this route of vaccination using inactivated urinary tract pathogens resulted in an increased IgA response in vaginal and urinary secretions with a decrease in clinically apparent re-infection. Uehling et al. (1991); Uehling et al. (1994) J. Urol. 151:213. Similarly in mice, attenuated strains of HSV-2 applied intravaginally induced humoral (particularly, immunization-stimulated IgG) and cellular immunity in both sera and vaginal secretions. Parr et al. (1997); McDermott et al. (1970) J. Gen. Virol. 71:1497–1504. Vaginally-administered mucosal adjuvants, in particular cholera toxin β-subunit, significantly raise IgA and IgG levels in the genital mucosa. (Johannsson et al. (1998) Inf. Immun. 66:514–520. These studies support the concept that mucosal associated lymphoid tissue participates in the generation of local immune-mediated protection. Furthermore, unlike parenteral vaccines, mucosal vaccination, such as a vaginal delivery, precludes the necessity of a pyrogen-free vaccine, causes fewer adverse reactions, and is amenable to routine booster immunizations.
Administration of certain DNA sequences, generally known as immunostimulatory sequences or “ISS,” induces an immune response with a Th1-type bias as indicated by secretion of Th1-associated cytokines. The Th1 subset of helper cells is responsible for classical cell-mediated functions such as delayed-type hypersensitivity and activation of cytotoxic T lymphocytes (CTLs), whereas the Th2 subset functions more effectively as a helper for B-cell activation. The type of immune response to an antigen is generally influenced by the cytokines produced by the cells responding to the antigen. Differences in the cytokines secreted by Th1 and Th2 cells are believed to reflect different biological functions of these two subsets See, for example, Romagnani (2000) Ann. Allergy Asthma Immunol. 85:9–18.
Administration of an immunostimulatory polynucleotide with an antigen results in a Th1-type immune response to the administered antigen. Roman et al. (1997) Nature Med. 3:849–854. For example, mice injected intradermally with Escherichia coli (E. coli) β-galactosidase (β-Gal) in saline or in the adjuvant alum responded by producing specific IgG1 and IgE antibodies, and CD4+ cells that secreted IL-4 and IL-5, but not IFN-γ, demonstrating that the T cells were predominantly of the Th2 subset. However, mice injected intradermally (or with a tyne skin scratch applicator) with plasmid DNA (in saline) encoding β-Gal and containing an ISS responded by producing IgG2a antibodies and CD4+ cells that secreted IFN-γ, but not IL-4 and IL-5, demonstrating that the T cells were predominantly of the Th1 subset. Moreover, specific IgE production by the plasmid DNA-injected mice was reduced 66–75%. Raz et al. (1996) Proc. Natl. Acad. Sci. USA 93:5141–5145 In general, the response to naked DNA immunization is characterized by production of IL-2, TNFα and IFN-γ by antigen-stimulated CD4+ T cells, which is indicative of a Th1-type response. This is particularly important in treatment of allergy and asthma as shown by the decreased IgE production. The ability of immunostimulatory polynucleotides to stimulate a Th1-type immune response has been demonstrated with bacterial antigens, viral antigens and with allergens (see, for example, WO 98/55495).
Other references describing ISS include: Krieg et al. (1989) J. Immunol. 143:2448–2451; Tokunaga et al. (1992) Microbiol. Immunol. 36:55–66; Kataoka et al. (1992) Jpn. J. Cancer Res. 83:244–247; Yamamoto et al. (1992) J. Immunol. 148:4072–4076; Mojcik et al. (1993) Clin. Immuno. and Immunopathol. 67:130–136; Branda et al. (1993) Biochem. Pharmacol. 45:2037–2043; Pisetsky et al. (1994) Life Sci. 54(2):101–107; Yamamoto et al. (1994a) Antisense Research and Development. 4:119–122; Yamamoto et al. (1994b) Jpn. J. Cancer Res. 85:775–779; Raz et al. (1994) Proc. Natl. Acad. Sci. USA 91:9519–9523; Kimura et al. (1994) J. Biochem. (Tokyo) 116:991–994; Krieg et al. (1995) Nature 374:546–549; Pisetsky et al. (1995) Ann. N.Y. Acad. Sci. 772:152–163; Pisetsky (1996a) J. Immunol. 156:421–423; Pisetsky (1996b) Immunity 5:303–310; Zhao et al. (1996) Biochem. Pharmacol. 51:173–182; Yi et al. (1996) J. Immunol. 156:558–564; Krieg (1996) Trends Microbiol. 4(2):73–76; Krieg et al. (1996) Antisense Nucleic Acid Drug Dev. 6:133–139; Klinman et al (1996) Proc. Natl. Acad. Sci. USA. 93:2879–2883; Raz et al. (1996); Sato et al. (1996) Science 273:352–354; Stacey et al. (1996) J. Immunol. 157:2116–2122; Ballas et al. (1996) J. Immunol. 157:1840–1845; Branda et al. (1996) J. Lab. Clin. Med. 128:329–338; Sonehara et al. (1996) J. Interferon and Cytokine Res. 16:799–803; Klinman et al. (1997) J. Immunol. 158:3635–3639; Sparwasser et al. (1997) Eur. J. Immunol. 27:1671–1679; Roman et al. (1997); Carson et al. (1997) J. Exp. Med. 186:1621–1622; Chace et al. (1997) Clin. Immunol. and Immunopathol. 84:185–193; Chu et al. (1997) J. Exp. Med. 186:1623–1631; Lipford et al. (1997a) Eur. J. Immunol. 27:2340–2344; Lipford et al. (1997b) Eur. J. Immunol. 27:3420–3426; Weiner et al. (1997) Proc. Natl. Acad. Sci. USA 94:10833–10837; Macfarlane et al. (1997) Immunology 91:586–593; Schwartz et al. (1997) J. Clin. Invest. 100:68–73; Stein et al. (1997) Antisense Technology, Ch. 11 pp. 241–264, C. Lichtenstein and W. Nellen, Eds., IRL Press; Wooldridge et al. (1997) Blood 89:2994–2998; Leclerc et al. (1997) Cell. Immunol. 179:97–106; Kline et al. (1997) J. Invest. Med. 45(3):282A; Yi et al. (1998a) J. Immunol. 160:1240–1245; Yi et al. (1998b) J. Immunol. 160:4755–4761; Yi et al. (1998c) J. Immunol. 160:5898–5906; Yi et al. (1998d) J. Immunol. 161:4493–4497; Krieg (1998) Applied Antisense Oligonucleotide Technology Ch. 24, pp. 431–448, C. A. Stein and A. M. Krieg, Eds., Wiley-Liss, Inc.; Krieg et al. (1998a) Trends Microbiol. 6:23–27; Krieg et al. (1998b) J. Immunol. 161:2428–2434; Krieg et al. (1998c) Proc. Natl. Acad. Sci. USA 95:12631–12636; Spiegelberg et al. (1998) Allergy 53(45S):93–97; Homer et al. (1998) Cell Immunol. 190:77–82; Jakob et al. (1998) J. Immunol. 161:3042–3049; Redford et al. (1998) J. Immunol. 161:3930–3935; Weeratna et al. (1998) Antisense & Nucleic Acid Drug Development 8:351–356; McCluskie et al. (1998) J. Immunol. 161(9):4463–4466; Gramzinski et al. (1998) Mol. Med. 4:109–118; Liu et al. (1998) Blood 92:3730–3736; Moldoveanu et al. (1998) Vaccine 16: 1216–1224; Brazolot Milan et al (1998) Proc. Natl. Acad. Sci. USA 95:15553–15558; Broide et al. (1998) J. Immunol. 161:7054–7062; Broide et al. (1999) Int. Arch. Allergy Immunol. 118:453–456; Kovarik et al. (1999) J. Immunol. 162:1611–1617; Spiegelberg et al. (1999) Pediatr. Pulmonol. Suppl. 18:118–121; Martin-Orozco et al. (1999) Int. Immunol. 11:1111–1118; EP 468,520; WO 96/02555; WO 97/28259; WO 98/16247; WO 98/18810; WO 98/37919; WO 98/40100; WO 98/52581; WO 98/55495; WO 98/55609 and WO 99/11275. See also Elkins et al. (1999) J. Immunol. 162:2291–2298, WO 98/52962, WO 99/33488, WO 99/33868, WO 99/51259 and WO 99/62923. See also Zimmermann et al. (1998) J. Immunol. 160:3627–3630; Krieg (1999) Trends Microbiol. 7:64–65; U.S. Pat. Nos. 5,663,153, 5,723,335, 5,849,719 and 6,174,872. See also WO 99/56755, WO 00/06588, WO 00/16804; WO 00/21556; WO 00/67023 and WO 01/12223.
There exists a need in the art for effective treatments of herpes virus infections.
All publications and patent applications cited herein are hereby incorporated by reference in their entirety.